First,
the authors observed that there was rhythmic variation of gut
microbiota composition wild-type mice due to dark-light cycle, that
was lost in Per1/2−/− mice,
which are deficient in a functional host clock genes. Interestingly,
artificially modulating food availability could alleviate circadian
clock deficiency in Per1/2−/− mice.

Finally,
the authors examined gut microbiota composition from individuals
undergoing jet-lag. Interestingly, during jet-lag phase there was an
increase in Firmicutes which were linked to obesity in earlier
studies. Moreover, gut flora taken collected during jet-lag phase but
not before or after, could promote metabolic syndrome in germ-free
mice.

In
summary, this study showed that human circadian rhythm control gut
microbiota composition which in turn influence development of
metabolic syndrome (weight gain, type II diabetes). It shows that
some of the effects of dark-light cycle disruption could be minimized
by antibiotic treatment. Of course, in this case antibiotic treatment
must be directed to specific gut microbiota species. In addition,
this study indicates that modulating or restricting access to food to
particular time periods could minimize effect of dark-light cycle
disruption in humans.